W02-358-4004 Firestone Cab Air Shock Absorber Style 4004 Suspension Air Spring Replacement

• Firestone Style: 4004
• Firestone Number: W023584004
• Firestone Number: W02 358 4004
• Firestone Number: W02-358-4004
• Firestone Number: WO23584004
• Firestone Number: WO2 358 4004
• Firestone Number: WO2-358-4004

• The top cover plate diameter: 1.65"
• Air fitting: 1/8NPT
• Piston width: 1.38"
• Threaded hole: 3/8-16
• Max. outer diameter: 3.1"
• Design height: 5.5"
• Min. height: 3.6"
• Max. height: 9"

To ensure reliable performance in demanding commercial vehicle applications, each air suspension component undergoes strict quality control and inspection procedures before leaving the factory.

Every air spring is subjected to multiple tests, including:

• Air Tightness Testing: Each unit is pressurized and monitored to ensure there is no leakage from the rubber bellows, crimped edges, or air fittings.
• Burst Pressure and Structural Integrity Testing: The air spring is tested under high internal pressure to verify that the reinforced rubber and metal components can withstand extreme operating conditions without failure.
• Fatigue and Durability Testing: Repeated compression and extension cycles are simulated to evaluate long-term performance and resistance to material fatigue.
• Dimensional and Mounting Inspection: Critical dimensions such as mounting hole spacing, plate diameter, and height range are checked to ensure proper fitment and interchangeability with original equipment parts.

The rubber air sleeve is produced using multi-layer reinforced elastomer compounds designed to resist:

• Cracking caused by temperature fluctuations
• Ozone and environmental aging
• Continuous flexing and pressure cycling during daily operation

Metal components are treated to improve corrosion resistance, helping extend service life in harsh road and weather environments.

All air springs are backed by a 12-month warranty from the date of shipment. During this period, products found to have manufacturing defects under normal operating conditions are eligible for replacement or technical support.

This warranty provides customers and fleet operators with added confidence when selecting replacement air suspension components for their vehicles.